Duplex automatic sheet feeder

ABSTRACT

In a duplex automatic sheet feeder, a first passageway is connected to a sheet input tray for storing sheets. A sheet feeding mechanism feeds the sheets one by one to the first passageway. A second passageway is connected to the first and third passageways and has an image processing region. A fourth passageway is connected to the third passageway and the second passageway. A fifth passageway is connected to the third passageway and a duplex sheet output tray. A guiding mechanism located at a connection portion between the third and fifth passageways selectively guides the sheet from the third passageway to the fifth passageway. A sheet detector located at the third passageway detects the sheet moving through the third passageway. A transporting mechanism transports the sheet from the first passageway to the duplex sheet output tray sequentially through the second, third, fourth, third and fifth passageways.

BACKGROUND OF THE INVENTION

1. Field of Invention

The invention relates to a duplex automatic sheet feeder, and moreparticularly to a duplex automatic sheet feeder capable of effectivelypreventing an ultra-thin sheet from buckling in a sheet passageway.

2. Related Art

In a conventional duplex scanner, an automatic sheet feeder usually hasto turn a document thrice and transport the document through a scanningregion thrice when the document is being scanned. When the document istransported across the scanning region at the first time, a front sideof the document is scanned. When the document is transported across thescanning region at the second time, a backside of the document isscanned. When the document is transported across the scanning region atthe third time, no scanning operation is carried out. The third documenttransporting operation is, carried out in order to keep the same orderof the documents.

Thus, a next document cannot be fed until the current document istransported across the scanning region at the third time in each scanprocedure. A lot of unessential waiting time is wasted so that thescanning operation cannot be carried rapidly in this conventionalautomatic sheet feeder.

In addition, many branch passageways are formed on the documenttransporting path for the purpose of turning over the sheet smoothly. Inorder to make the document travelling path become unidirectional, anelastic Mylar has to be disposed at the branching portion. The elasticMylar may be pushed away by the sheet moving in a first direction, andguides the sheet, which is moving in a direction opposite to the firstdirection, to another branch passageway. In this case, when the sheet istoo thin to have the sufficient rigidity, the sheet cannot push theelastic Mylar away and may buckle and be jammed in the passageway.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a duplex automaticsheet feeder capable of effectively preventing an ultra-thin sheet frombuckling in a sheet passageway.

To achieve the above-identified object, the invention provides a duplexautomatic sheet feeder including a sheet input tray, a first passageway,a sheet feeding mechanism, a second passageway, a third passageway, afourth passageway, a fifth passageway, a sheet output tray, a guidingmechanism, a sheet detector and a transporting mechanism. The sheetinput tray stores a plurality of sheets. The first passageway isconnected to the sheet input tray. The sheet feeding mechanism feeds thesheets one by one to the first passageway. The second passageway isconnected to the first passageway and has an image processing region.The third passageway is connected to the second passageway. The fourthpassageway is connected to the third passageway and the secondpassageway. The fifth passageway is connected to the third passageway.The sheet output tray is connected to the fifth passageway. The guidingmechanism is located at a connection portion between the thirdpassageway and the fifth passageway, and is for selectively guiding thesheet from the third passageway to the fifth passageway. The sheetdetector is located at the third passageway and is for detecting thesheet moving through the third passageway. The transporting mechanism isfor transporting the sheet from the first passageway to the sheet outputtray sequentially through the second passageway, the third passageway,the fourth passageway, the second passageway, the third passageway andthe fifth passageway.

Further scope of the applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a schematic illustration showing a duplex automatic sheetfeeder according to a first embodiment of the invention;

FIG. 2 is a schematic illustration showing a duplex automatic sheetfeeder according to a second embodiment of the invention;

FIG. 3 is a schematic illustration showing a duplex automatic sheetfeeder according to a third embodiment of the invention;

FIG. 4 is a schematic illustration showing a duplex automatic sheetfeeder according to a fourth embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be apparent from the following detaileddescription, which proceeds with reference to the accompanying drawings,wherein the same references relate to the same elements.

FIG. 1 is a schematic illustration showing a duplex automatic sheetfeeder 1 according to a first embodiment of the invention. Referring toFIG. 1, the duplex automatic sheet feeder 1 of this embodiment includesa sheet input tray 10, a first passageway 21 (from points A to B), asheet feeding mechanism 30, a second passageway 22 (from points B to C),a third passageway 23 (from points C to 23A), a fourth passageway 24(from points C to B), a fifth passageway 25, a sheet output tray 40, aguiding mechanism 50, an elastic guide 52, a sheet detector 60 and atransporting mechanism 70.

The sheet input tray 10 stores a plurality of sheets S. In thisembodiment, the uppermost sheet is first fed. The first passageway 21 isconnected to the sheet input tray 10. The sheet feeding mechanism 30feeds the sheets S one by one to the first passageway 21. In thisembodiment, the sheet feeding mechanism 30 includes a pickup roller 31and a separation roller set 32.

The second passageway 22 is connected to the first passageway 21 and hasan image processing region 22A. In this embodiment, the image processingregion 22A is a scanning region, and a sheet (document or original)moving across this region is scanned by an optical module 90. In anotherembodiment, the image processing region 22A is a printing region, and aprinting module prints data on a sheet moving across this region.

The third passageway 23 is connected to the second passageway 22 so thatthe sheet can enter the third passageway 23 from the second passageway22. The fourth passageway 24 is connected to the third passageway 23 andthe second passageway 22, and the sheet coming from the third passageway23 can enter the fourth passageway 24 but cannot enter the secondpassageway 22. The fifth passageway 25 is connected to the thirdpassageway 23 so that the sheet coming from the third passageway 23 canenter the fifth passageway 25.

The sheet output tray 40 is connected to the fifth passageway 25 andstores the sheets after being scanned. The guiding mechanism 50 mayswing and is located at a connection portion 26 between the thirdpassageway 23 and the fifth passageway 25 to selectively guide the sheetS from the third passageway 23 to the fifth passageway 25. The elasticguide 52 guides the sheet S from the third passageway 23 to the fourthpassageway 24, prevents the sheet S coming from the third passageway 23from entering the second passageway 22, and allows the sheet S to enterthe third passageway 23 from the second passageway 22. The sheetdetector 60 located at the third passageway 23 is for detecting thesheet S moving through the third passageway 23. The sheet detector 60may be a reflective or transmissive detector and outputs an infraredlight ray, for example, to detect whether a leading edge or a trailingedge of the sheet has passed through a specific position to serve as areference for feeding another sheet.

The transporting mechanism 70 includes a plurality of rollers 71 to 79.In a duplex scan mode, the transporting mechanism 70 transports thesheet S from the first passageway 21 to the duplex sheet output tray 40sequentially through the second passageway 22, the third passageway 23,the fourth passageway 24, the second passageway 22, the third passageway23 and the fifth passageway 25. When the sheet enters the thirdpassageway 23 from the second passageway 22, the elastic guide 52 isslightly pushed away by the sheet, and the state of the guidingmechanism 50 is shown by the dashed line profile. When the sheet entersthe fourth passageway 24 from the third passageway 23, the state of theguiding mechanism 50 is shown by the dashed line profile, and theelastic guide 52 is in close contact with the connection portion 26.Thus, the elastic guide 52 can guide the sheet S from the thirdpassageway 23 to the fourth passageway 24. When the sheet enters thefifth passageway 25 from the third passageway 23, the state of theguiding mechanism 50 is shown by the solid line profile.

In this embodiment, the third passageway 23 is also connected to thesheet output tray 40. In a simplex scan mode, the transporting mechanism70 may further transport the sheet S from the first passageway 21 to thesheet output tray 40 sequentially through the second passageway 22 andthe third passageway 23. An outlet 23A of the third passageway 23 isfarther from the sheet output tray 40 than an outlet 25A of the fifthpassageway 25.

FIG. 2 is a schematic illustration showing a duplex automatic sheetfeeder according to a second embodiment of the invention. Referring toFIG. 2, the duplex automatic sheet feeder according to this embodimentfurther includes a simplex sheet output tray 80, which is connected tothe third passageway 23, for transporting the sheet S from the firstpassageway 21 to the simplex sheet output tray 80 sequentially throughthe second passageway 22 and the third passageway 23 in a simplex mode.In this embodiment, the simplex sheet output tray 80 is located at alevel higher than the sheet output tray 40. Consequently, the user mayidentify whether the documents or sheets have been processed in adesired simplex or duplex manner according to the tray in which thedocuments or sheets are placed.

It is to be noted that the elastic guide 52 may be replaced with asub-guiding mechanism (not shown), which is similar to the guidingmechanism 50 and may swing, for guiding the sheet S from the thirdpassageway 23 to the fourth passageway 24 and guiding the sheet S fromthe second passageway 22 to the third passageway 23. Because thesub-guiding mechanism is similar to the guiding mechanism 50 and theposition thereof is the same as that of the elastic guide 52, thedetailed arrangement thereof will be omitted.

In addition, in order to shorten the time of continuously transportingthe sheets, the second sheet can be fed into the first passageway 21after the second side of the first sheet is scanned and after thetrailing edge of the first sheet is moved from the fourth passageway 24and past the point B.

FIG. 3 is a schematic illustration showing a duplex automatic sheetfeeder according to a third embodiment of the invention. Referring toFIG. 3, the duplex automatic sheet feeder 1 of this embodiment includesa sheet input tray 10, a first passageway 21 (from points A to B), asheet feeding mechanism 30, a second passageway 22 (from points B to C),a third passageway 23 (from points C to 23A), a fourth passageway 24(from points C to B), a fifth passageway 25, a duplex sheet output tray40, a guiding mechanism 50, a sheet detector 60 and a transportingmechanism 70.

The sheet input tray 10 stores a plurality of sheets S. In thisembodiment, the uppermost sheet is first fed. The first passageway 21 isconnected to the sheet input tray 10. The sheet feeding mechanism 30feeds the sheets S one by one to the first passageway 21. In thisembodiment, the sheet feeding mechanism 30 includes a pickup roller 31and a separation roller set 32.

The second passageway 22 is connected to the first passageway 21 and hasan image processing region 22A. In this embodiment, the image processingregion 22A is a scanning region, and a sheet (document or original)moving across this region is scanned by an optical module 90. In anotherembodiment, the image processing region 22A is a printing region, and aprinting module prints data on a sheet moving across this region.

The third passageway 23 is connected to the second passageway 22 so thatthe sheet can enter the third passageway 23 from the second passageway22. The fourth passageway 24 is connected to the third passageway 23 andthe second passageway 22, and the sheet coming from the third passageway23 can enter the fourth passageway 24 but cannot enter the secondpassageway 22. The fifth passageway 25 is connected to the thirdpassageway 23 so that the sheet coming from the third passageway 23 canenter the fifth passageway 25.

The duplex sheet output tray 40 is connected to the fifth passageway 25and stores the sheets after being scanned in a duplex manner. Theguiding mechanism 50 is located at a connection portion 26 between thethird passageway 23 and the fifth passageway 25 to selectively guide thesheet S from the third passageway 23 to the fifth passageway 25. Thesheet detector 60 located at the third passageway 23 is for detectingthe sheet S moving through the third passageway 23. The sheet detector60 may be a reflective or transmissive detector and outputs an infraredlight ray, for example, to detect whether a leading edge or a trailingedge of the sheet has passed through a specific position to serve as areference for feeding another sheet.

The transporting mechanism 70 includes a plurality of rollers 71 to 79.In a duplex scan mode, the transporting mechanism 70 transports thesheet S from the first passageway 21 to the duplex sheet output tray 40sequentially through the second passageway 22, the third passageway 23,the fourth passageway 24, the second passageway 22, the third passageway23 and the fifth passageway 25. When the sheet enters the thirdpassageway from the second passageway, the state of the guidingmechanism 50 is shown by the upper dashed line profile. Thus, theguiding mechanism 50 may further guide the sheet S from the secondpassageway 22 to the third passageway 23. When the sheet enters thefourth passageway from the third passageway, the state of the guidingmechanism 50 is shown by the lower dashed line profile. Thus, theguiding mechanism 50 may guide the sheet S from the third passageway 23to the fourth passageway 24. When the sheet enters the fifth passagewayfrom the third passageway, the state of the guiding mechanism 50 isshown by the solid line profile. It is to be noted that the guidingmechanism 50 may only have two states as indicated by the upper dashedline profile and the solid line profile, and the structure of thepassageway may be properly designed to make the sheet enter the fourthpassageway from the third passageway smoothly.

In this embodiment, the third passageway 23 is also connected to theduplex sheet output tray 40. In a simplex scan mode, the transportingmechanism 70 may further transport the sheet S from the first passageway21 to the duplex sheet output tray 40 sequentially through the secondpassageway 22 and the third passageway 23. An outlet 23A of the thirdpassageway 23 is farther from the duplex sheet output tray 40 than anoutlet 25A of the fifth passageway 25.

FIG. 4 is a schematic illustration showing a duplex automatic sheetfeeder according to a fourth embodiment of the invention. Referring toFIG. 4, the duplex automatic sheet feeder of this embodiment furtherincludes a simplex sheet output tray 80, which is connected to the thirdpassageway 23, for transporting the sheet S from the first passageway 21to the simplex sheet output tray 80 sequentially through the secondpassageway 22 and the third passageway 23 in a simplex mode. In thisembodiment, the simplex sheet output tray 80 is located at a levelhigher than the duplex sheet output tray 40. Consequently, the user mayidentify whether the documents or sheets have been processed in adesired simplex or duplex manner according to the tray in which thedocuments or sheets are placed.

In the duplex automatic sheet feeder of the invention, the guidingmechanism is provided to guide the moving direction of the sheet, so thethin sheet is free from the conventional buckling phenomenon. Inaddition, two sheet output trays are provided so that the user canfurther identify whether the documents or sheets have been processed ina desired simplex or duplex manner. Thus, the feeder of the inventionmay be used in a quite convenient and human-oriented manner.

While the invention has been described by way of examples and in termsof preferred embodiments, it is to be understood that the invention isnot limited thereto. To the contrary, it is intended to cover variousmodifications. Therefore, the scope of the appended claims should beaccorded the broadest interpretation so as to encompass all suchmodifications.

1. A duplex automatic sheet feeder, comprising: a sheet input tray forstoring a plurality of sheets; a first passageway connected to the sheetinput tray; a sheet feeding mechanism for feeding the sheets one by oneto the first passageway; a second passageway, which is connected to thefirst passageway and has an image processing region; a third passagewayconnected to the second passageway; a fourth passageway connected to thethird passageway and the second passageway; a fifth passageway connectedto the third passageway; a sheet output tray connected to the fifthpassageway; a guiding mechanism, located at a connection portion betweenthe third passageway and the fifth passageway, for selectively guidingthe sheet from the third passageway to the fifth passageway; a sheetdetector, located at the third passageway, for detecting the sheetmoving through the third passageway; and a transporting mechanism fortransporting the sheet from the first passageway to the sheet outputtray sequentially through the second passageway, the third passageway,the fourth passageway, the second passageway, the third passageway andthe fifth passageway.
 2. The feeder according to claim 1, wherein thethird passageway is connected to the sheet output tray, and in a simplexmode, the transporting mechanism may further transport the sheet fromthe first passageway to the sheet output tray sequentially through thesecond passageway and the third passageway.
 3. The feeder according toclaim 2, wherein an outlet of the third passageway is farther from thesheet output tray than an outlet of the fifth passageway.
 4. The feederaccording to claim 1, further comprising a simplex sheet output tray,connected to the third passageway, for transporting the sheet from thefirst passageway to the simplex sheet output tray sequentially throughthe second passageway and the third passageway in a simplex mode.
 5. Thefeeder according to claim 4, wherein the simplex sheet output tray islocated at a level higher than the sheet output tray.
 6. The feederaccording to claim 1, wherein the guiding mechanism further guides thesheet from the third passageway to the fourth passageway.
 7. The feederaccording to claim 1, wherein the guiding mechanism further guides thesheet from the second passageway to the third passageway.
 8. The feederaccording to claim 1, further comprising: an elastic guide for guidingthe sheet from the third passageway to the fourth passageway.
 9. Thefeeder according to claim 1, further comprising: a sub-guidingmechanism, which may swing to guide the sheet from the third passagewayto the fourth passageway or from the second passageway to the thirdpassageway.